Missile steering control



April 12, 1966 J. c. MCEWEN 3,245,620

MISSILE STEERING CONTROL Filed Dec. l5, 1961 INVENTOR.

I BY (M5/522 @5226211621 A e/Ww United States Patent 3,245,620 MISSLESTEERING CONTRL John C. McEwen, Indianapolis, ind., assigner to GeneralMotors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec.13, 1961, Ser. No. 159,091) 2 Claims. (Cl. Z39-6525) This inventionrelates to a guidance control for a missile or the like and moreparticularly to a steering mechanism for a missile having a number offixed or nonorienting exhaust nozzles.

An object of the invention is to provide a steering control for amissile that is simple in construction and eco- `nomical to manufacture,and one that changes the attitude of the missile by control of themissile fluid exhaust stream.

A further object of the invention is to provide a missile having aguidance control combined with a unique exhaust nozzle constructiondesigned to prevent erosion of the nozzle surfaces.

A still further object of the invention is to provide a missleconstruction consisting of a number of fixed fluid jet exhaust nozzlessymmetrically disposed around the axis of the missile including anapparatus selectively movable to block` the passage of the exhaust fluidthrough some of the nozzles to thereby create a jet turning force on themissile upon the passage of fluid through the unblocked nozzles. v

lt is a further object of the invention to provide missile attitudecontrol by an apparatus controlling the missile -jet exhaust streamwhile maintaining `the losses in thrust occasioned by this control at aminimum.

Other objects, features and advantages will become apparent uponreference to the succeeding detailed description of the invention and tothe drawings illustrating the preferred embodiments thereof, wherein,

FIGURE l is a cross sectional View of a portion of the exhaust end of :amissile taken on a plane indicated by and viewed in the direction of thearrows 1-1 of FIG- URE 2,

FIGURE 2 is a cross sectional View on a reduced scale taken on a planeindicated by and viewed in the direction of the arrows 2 2 of FIGURE 1,FIGURE 3 is a View of a portion of FIGURE 1 illustrating a modificationthereof, and

FIGURE 4 is a cross sectional View corresponding to FIGURE 2illustrating the modification of FIGURE 3.

The invention provides a guidance system for a rocket or the like havinga number of fixed or nonorienting gas jet exhaust nozzles. It consistsin general of a control apparatus rotatably mounted on the outlet end ofthe rocket to partially or completely block off one or more of theinlets to the nozzles so that an unbalance or difierential in thrust iscreated between the gases flowing out of the different nozzles to effecta jet turning force on a rocket.

More specifically, FIGURE 1, which is essentially to scale, shows theaft or outlet end of an -annular rocket casing closed by an annularplate 12. Plate 12 may be secured to the casing in any suitable manner(not shown). The plate has three (FIG. 2) spaced clusters of gas jetmetering holes 14 to permit the escape of gas through the plate. Each ofthe clusters is spaced 120 apart around the plate and an equal radialdistance from the rocket longitudinal axis 15. The holes 14 in each ofthe clusters are equally spaced from each other and an equal distanceradially from a centerline 16. Each of the centerlines 16 coincides withthe longitudinal axis of a fixed convergent-divergent jet exhaust nozzle18. The nozzles are secured to the downstream side of plate 12 by anysuitable means such as flanges 19, and project .predetermined flightpath is provided as follows.

axially downstream therefrom. The nozzles are symmetrically disposedaround the closure plate in the same relationship to each other as theclusters of holes.

Each of the nozzles 18 is of the same size and has its inlet 2f)covering a cluster of holes 14 with which it is aligned. Each has aconverging inlet wall 24, a venturi or throat 26, and a bell shapeddiverging outlet wall 27. A conical inner body or plug 2S is fixed toplate 12 on the centerline of the nozzle and projects axially into theiniet 20. The nozzle converging wall 24 together with the plug 28 andholes 14 in effect form three tubular-like guide passages 3l) eachangularly disposed with respect to the nozzle centerline. The passages30 may be considered as separated at the holes 14 while having a commonoutlet 34 at their opposite ends at the vertex 36 of the throat of thenozzle.

The throat of each nozzle is so sized that its area is, for example,equal to approximately fifty percent of the total area of the inletholes 14. Thus, the gases have sufcient velocity imparted to them asthey pass into and through the passages 30 so that they flow insubstantially a straight path towards the vertex of the throat withoutdiffusing into each other, i.e., into the area around the plug 28. Theproportioning of the plug and nozzle walls therefore provides a kineticconvergent flow of the gases at the vertex point 36 in the throat asshown by the arrows 38 in FIGURE l, thereby preventing the gases fromscraping and eroding the throat surface.

.As will be described in more detail later, the blocking of any one orall of the holes 14 of a cluster by an apparatus to be describedcontrols the volume of gas passing into the particular nozzle associatedwith the cluster. The thrust imparted by the flow of gas through thisnozzle is therefore either reduced or terminated as compared to the fiowthrough the unblocked nozzles. This unbalance in thrust effects steeringof the rocket.

The chamber 49 defined by the aft end of casing 1@ and the closure plate12 may be the aft end of a combustion chamber from which the combustionproduct gases will flow out through the nozzles 18; or, the chamber maybe, for example, the outlet duct for the gases emanating from acombustion chamber or turbine section located upstream of the closureplate. ln either case, under normal operation, the same volume ofexhaust gases will flow out through each of the holes 14 and nozzles 18to impart an axial thrust to the rocket. The thrust forces around theoutlet are therefore balanced.

Attitude control of the rocket for maintaining it on a As statedpreviously, the inlets to some of the nozzles are adapted to be eitherpartially or completely blocked to create an unbalance in thrust betweenthe flow of gases out of the different nozzles, thereby providing a jetturning force on the rocket. To accomplish this, a relatively fiathollow circular plate 42 is mounted to slide over the face 44 of theclosure plate 12 to either partially or completely block one or more ofthe holes 14 of any one cluster of holes.

FIGURES l and 2 show the plate 42 formed integral with a hollowsupporting arm 46 secured to a hollow shaft 48 rotatably mounted on theaxis 15 of the closure plate. The shaft and arm are secured to therotatable portion 56 of a journal bearing S2, the mating stationaryportion 54 being formed as a boss or hub projecting from the closureplate. Bearing portion 50 has two radially spaced annular flanges 56rotatably fitted into mating grooves 58 formed in the portion 54.

Arm 46 and the blockage plate are supported for rotation around plate 12by an anti-friction load bearing 60 having its inner race secured to thearm and its outer race resting against the closure plate face. Thebearing supports the arm 46 and plate 42 against the force of the .35exhaust gases acting on them from within the chamber 4t) and providesthe necessary axial clearance to permit the arm and plate to translatefreely in a circular path around the face of closure plate l2.

The integral portion 61 connecting the arm 46 and the blockage plate 42is shown bent or offset so that the plate 42 lies substantially flatagainst the face of the closure plate. While not shown, it is within thescope of the invention to provide the portions of blockage plate 42 andarm 46 that face the closure plate 12 with grooves or pockets that lareopen to the gas pressure in chamber 40 to balance the loadings on theintegral arm and plate, thereby reducing the forces required to rotatethem.

The hollow interior of plate 42 and arm 46 are adapted to be filledwith, in this case, a solid coolant 62, such as a synthetic polymericamide of which nylon is an example, to insulate the plate and `arm fromthe hot exhaust gases in chamber 46. Nylon is a convenient coolantbecause it vaporizes at a temperature below the nozzle operatingtemperature. The hollow shaft 43, which opens into the arm 45, acts as avent for the release of the gases produced upon vaporizing of thecoolant by the heat of the exhaust gases on the plate and arm. Othersuitable coolants, both liquids and solids, could be used as a matter ofchoice without departing from the scope of the invention.

The arm and blockage plate are variably rotated by a worm gear drivemechanism including gear 63 splined to shaft 4S and meshing with theworm shaft 64 of an electric motor 66. The control mechanism for theautomatic intermittent operation of motor 66 is not shown since it isknown and is unnecessary for an understanding of this invention. Suiceit to say, however, that the motor is activated in response to apredetermined signal from the control system indicating a necessity forattitude control of the rocket or missile, and is deactivated in thesame manner when the rocket attitude is in accordance with apredetermined schedule.

While the driving mechanism has been illustrated as an electric motor,it will be clear that other similar operating mechanisms, such ashydraulically operated devices, for example, could be used withoutdeparting from the scope of the invention.

For normal operation of the engine, the blockage plate 42 will bepositioned between clusters of holes as shown in dot-dash lines 70 inFIGURE 2 so as not to interfere with the normal exhaust of the gases outthrough the nozzles. The exhaust gases therefore pass out through all ofthe holes 14 in each of the three clusters to impart a pure axial thrustto the rocket, the thrust forces being balanced around the closureplate.

Attitude control of the rocket is accomplished, as stated previously, byproviding a thrust differential between the gases flowing out of thedifferent nozzles to provide a jet turning force on the aircraft.Therefore, the degree of rotation of the arm 4e and plate 42 will varyas a function of the turning forces necessary. For example, if only asmall turning force is necessary, the plate will'be rotated to close sayonly one hole 14 to provide a small thrust differential between nozzles;whereas, if a large turning force is needed, the plate will be rotatedto cornpletely block off all the holes of any one cluster.

Therefore, as seen in FIGURE 2, when the control system (not shown)indicates that attitude control is necessary, motor 66 is activated torotate shaft 48, arm 45, and the blocking plate 42 in nite increments toeither partially (dot-dash lines 80, FIG. 2) or completely block onehole I4 of a cluster. Upon continued rotation, the plate will partiallyor completely (full lines, FIG. 2) block all of the three holes 14 ofany one cluster at any one time. The progressive and cumulative blockingof the holes will therefore progressively decrease the flow of exhaustgases out through the nozzle associated with the cluster of holes,thereby decreasing the thrust through this particular nozzle as comparedto the thrust resulting 4 from the passage of gases through theremaining unblocked nozzles.

In the case where only one or more but not allof the holes of a clusterare covered by the plate 42, the gases in chamber 4) will then pass intothe unblocked or only partially blocked tube-like passages 30, will havea kinetic convergence at the vertex of the throat of the nozzle, andwill be expanded uniformly o-ut the bellshaped exit portion of thenozzle. By a kinetic convergence is meant that the convergence of theangular forces of the gases passing through the holes 14 and passagesSi) are utilized so that the masses converge together at the vertex ofthe nozzle throat and are compressed through the nozzle. The gases, ofcourse, will pass out through all of the passages 30 in the othernozzles Without interference. rfhus, a jet turning force is created bythe greater increments of thrust resulting from the tlow of the gasesthrough the other nozzles, these greater thrust forces acting to turnthe rocket about its pivotal axis (not shown). The choice of the nozzleto be partially or completely blocked of course will depend upon whichdirection the rocket is to be turned. The rocket is therefore capable ofbeing turned in a 360 orbital path.

It should be noted that if a solid propellant is used as a fuel toproduce the exhaust gases in chamber 4%, blocking off all of the holesin a cluster will result in 'a pressure rise in chamber 4t? which willincrease the burn rate of the propellant and the generation of gases.Thus, more effective vectoring forces will be obtained. If lessvectoring is desired, only one of the holes 14 would be blocked offthereby resulting a minimum chamber pressure rise and the leastadditional generation of gases.

The FIGURES 1 and 2 construction illustrate a gas blocking plate capableof blocking all of the holes of any one cluster at one time. Amodication shownin FIGURES 3 and 4 illustrates the use of a blockagemember 42' capable of blocking only one hole of any one cluster of holesat any one time. The degree of control of the thrust differentialbetween the different nozzles .in this modification will therefore beless than that obtainable with the construction shown in FIGURES 1 and2. Since the details of the FIGURES 3 and 4 construction are otherwisethe same as the FIGURES l and 2 construction, land the operation differsonly in the partial or complete blocking of only one :hole at a timeinstead of more as shown in FIGURES 1 and 2, they will not be repeated.

While only one rotating blockage member is shown, it will be clear thatit is within they scope of the invention to provide two gas blockingmembersl movable either as a unit or separably to block two clusters ofholes at any one particular time to obtain even more finite attitudecontrol. Furthermore, it will be clear that more or less than threeclusters of gas outlet holes 14, and more or less than three holes inany one cluster could be provided without departure from the scope ofthe invention as long as the desired thrust differential is obtainable.It will also be clear that other forms of nozzles could be used with thegas blockage plate shown to obtain guidance control in a similar mannerwithout departing from the scope of the invention, such as, for example,nozzles not having plug type inlets. Also, the inlet portion of thenozzles could project into the chamber defined by the rocket casinginstead of being secured at their inlet ends to the closure plate asshown.

While the invention has been illustrated in this particular instance`for use with a rocket motor, it will be clear that it could be used inmany other installations and that many modifications may be made theretowithout departing from the scope of the invention.

From the foregoing, therefore, it will be seen that the inventionprovides a guidance system for .a missile or the like wherein niteattitude control of the missile is available by means of a simplemechanism controlling the exhaust stream in such a manner as to providea jet turning force on the rocket. It will also be seen that theinvention provides a reliable and practical rocket guidance controlwhile being economical to manufacture and simple in structure.

I claim:

1. An exhaust nozzle for a fluid reaction motor duct comprising aclosure member secured to and across the outlet end of said duct havingclusters of axially directed fluid jet exhaust openings therein, aplurality of iluid jet exhaust nozzles of the converging-diverging typesecured to said member each over a separate cluster of said openings forthe passage of exhaust iluid therethrough, the nozzles being similarlysized and uniformly distributed around the closure member to impartsubstantially equal increments of thrust to said motor in asubstantially axial direction upon the full flow of exhaust uid througheach of said nozzles, the total area of each cluster of said openingsbeing approximately twice the throat area of the corresponding exhaustnozzle, and control means secured to said motor and movable throughout arange of positions to variably control the flow of fluid throughselective ones of said nozzles providing a thrust differential betweenthe flow of fluid through lthe nozzles effecting a jet turning force onsaid duct providing attitude control thereof, each of said nozzleshaving Ia plug type inlet and a single outlet, the plug type inlet andthe outlet together with the closure member openings for each nozzleconstituting a plurality of tubular passages equi-angularly disposed andequally spaced with respect to each other and to the longitudinal laxisof said nozzle at one end, the opposite ends of the tubular passagesmeeting at a common vertex at the throat of said nozzle providing akinetic convergence of the fluid ow through said passages at saidthroat, said control means being movable to variably cover one of theopenings of the inlet of one of said nozzles, the exhaust uid passingthrough the uncovered holes and out through the nozzle outlet with anoverall reduction in the thrust imparted by the uid passing through theone nozzle.

2. An exhaust nozzle for a fluid reaction motor duct comprising aclosure member secured to and across the outlet end of said duct havingclusters of axially directed fluid jet exhaust openings therein, aplurality of fluid jet exhaust nozzles of the converging-diverging typesecured to said member each over a separate cluster of said openings,for the passage of exhaust fluid therethrough, the nozzles beingsimilarly sized and uniformly distributed around the closure member toimpart substantially equal increments of thrust to said motor in asubstantially axial direction upon the full flow of exhaust fluidthrough each of said nozzles, the total area of each cluster of saidopenings being approximately twice the throat area of the correspondingexhaust nozzle, and control means secured to said motor and movable tovariably control the flow of fluid through selective ones of saidnozzles providing a thrust differential between the flow of uid throughthe nozzles effecting a jet turning force on said duct providingattitude control thereof, each of said nozzles having a plug type inletand a single outlet, the plug type inlet and the outlet together withthe openings for each nozzle constituting a plurality of tubularpassages equi-angularly disposed and equally spaced with respect to eachother and to the longitudinal axis of said nozzle at one end, theopposite ends of the tubular passages meeting at -a common vertex at thethroat of said nozzle providing a kinetic convergence of the iiuid owthrough the passages at said throat, said control means being movablethroughout a range of positions variably and cumulatively covering oneor more of the openings into the inlet of one of said nozzles.

References Cited by the Examiner UNITED STATES PATENTS 2,612,747 10/1952Skinner 60-35.6 2,692,475 lO/ 1954 Hull -35.54 3,026,806 3/l962 Runtonet al 60-35.6 3,069,852 12/1962 Stricker 60-35.55

FOREIGN PATENTS 890,502 11/1943 France. 1,025,715 l/1953 France.

MARK NEWMAN, Primary Examiner SAMUEL LEVINE, Examiner.

1. AN EXHAUST NOZZLE FOR A FLUID REACTION MOTOR DUCT COMPRISING ACLOSURE MEMBER SECURED TO AND ACROSS THE OUTLET END OF SAID DUCT HAVINGCLUSTERS OF AXIALLY DIRECTED FLUID JET EXHAUST OPENINGS THEREIN, APLURALITY OF FLUID JET EXHAUST NOZZLES OF THE CONVERGING-DIVERGING TYPESECURED TO SAID MEMBER EACH OVER A SEPARATE CLUSTER OF SAID OPENINGS FORTHE PASSAGE OF EXHAUST FLUID THERETHROUGH, THE NOZZLES BEING SIMILARLYSIZED AND UNIFORMLY DISTRIBUTED AROUND THE CLOSURE MEMBER TO IMPARTSUBSTANTIALLY EQUAL INCREMENTS OF THRUST TO SAID MOTOR IN ASUBSTANTIALLY AXIAL DIRECTION UPON THE FULL FLOW OF EXHAUST FLUIDTHROUGH EACH OF SAID NOZZLES, THE TOTAL AREA OF EACH CLUSTER OF SAIDOPENINGS BEING APPROXIMATELY TWICE THE THROAT AREA OF THE CORRESPONDINGEXHAUST NOZZLE, AND CONTROL MEANS SECURED TO SAID MOTOR AND MOVABLETHROUGHOUT A RANGE OF POSITIONS TO VARIABLY CONTROL THE FLOW OF FLUIDTHROUGH SELECTIVE ONES OF SAID NOZZLES PROVIDING A THRUST DIFFERENTIALBETWEEN THE FLOW OF FLUID THROUGH THE NOZZLES EFFECTING A JET TURNINGFORCE ON SAID DUCT PROVIDING ATTITUDE CONTROL